Some people have experienced that sort of problem when there has been a mismatch between some odd detail of the way they entered their name on FB and on the booking. It could be something as minor as entering a middle name or not or using a different title (e.g. Dr if your FB registration says Mr, etc). So first thing to do would be to check that you enter details in exactly similar way. There have been other threads on this question btw so while I don't remember everything else that was said I'd recommend that you search them and check the rest of the advice/explanations given on those occasions. Good luck with getting your benefits recognised, and of course, do bring your card along which should ultimately trump any other information.